TIME-OF-FLIGHT MASS AND PHOTOELECTRON-SPECTROSCOPY STUDY OF LACN-

Mass spectra of LaCn- were taken by using a laser-vaporization source (LVS) and pulsed are cluster ion source (PACIS) applied to La-carbon c omposite rods (1:130 atomic ratio). The mass spectrum using the LVS wi th annealing procedure has shown several magic numbers for LaCn- (n = 44, 50, 60, and 70), whereas only small LaC-n (up to n = 14) have been observed in the mass spectrum using the PACIS. Photoelectron spectra of some of these have been measured using a magnetic-bottle type time- of-flight electron spectrometer. These results indicate the exsistence of a few conformational isomers for small La-containing carbon cluste r negative ions LaCn- (n = 5 - 8).